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Revised Control Strategy for Coal-Fired Power Plants During Transient Processes Considering Heat Transfer Deterioration of Cooling Wall: Flexibility Enhancement and Security Operation

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SSRN 2024年

作者： Wang, Dengliang Zhao, Yongliang Gao, Wei Chen, Weixiong Wang, Chaoyang Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Increasing share of power generation from intermittent renewable energy has resulted in an expanding demand for deep peaking and operational flexibility of thermal power plants. Under this circumstance, it causes an enormous threat to the safe operation of the boiler, especially cooling wall. So it is crucial to focus on the thermo-hydraulic performance of the cooling wall during transient processes. In this paper, a 1100 MW ultra-supercritical thermal power plant is used as the research object. A one-dimensional dynamic model of the cooling wall is constructed based on the conservation of mass, conservation of momentum, conservation of energy, state, metal heat storage and heat transfer equations. The temperature distributions of working fluid, inner and outer wall along the height direction of the cooling wall are obtained. Dry-out phenomenon of the cooling wall during the load cycling process is observed. It is found that heat transfer deterioration is a key reason for metal wall temperature intermittent fluctuation. When the load cycling rates are 2.5% Pe/min and 3.0% Pe/min, the maximum temperatures of metal tube wall during the loading up process reach 527.9°C and 557.3°C, respectively. Furthermore, a revised control strategy is proposed based on the heat transfer deterioration characteristics of the cooling wall. During the loading up process, the highest wall temperature is significantly reduced from 557.3°C to 502.2°C at 3.0% Pe/min. The maximum power ramp rate is increased from 2.5% Pe/min to 3.0% Pe/min when the revised control strategy is adopted. © 2024, The Authors. All rights reserved.

关键词： Fossil fuel power plants

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Thermodynamic Modeling and Analysis of the Hydrogen and Combustible Gas Production in Supercritical Water Partial Oxidation System of Coal

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SSRN 2024年

作者： Li, Yifeng Xing, Guowei Liu, Shi Guo, Shenghui Ge, Zhiwei Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Supercritical water partial oxidation (SCWPO) is an eco-friendly coal treatment technology that lowers the temperature needed for complete gasification of coal, promotes hydrogen output, enables targeted regulation of gaseous product composition, and eliminates gaseous pollutants. Current researches mainly focus on experiments and numerical simulations, with limited exploration in thermodynamics. he present study establishes an auto-thermal SCWPO cogeneration system for Hongliulin coal, employs sensitivity analysis to refine system parameters, and utilizes Life Cycle Assessment to evaluate environmental impact of hydrogen production system. As the outlet temperature of the reactor increases and the preheating water flow and equivalence ratio (ER) increase, the fraction of hydrogen in the gas product rises;conversely, the fraction of the combustible gas (CH4+CO+H2) rises. The SCWPO system can be precisely tailored to yield high-purity hydrogen or combustible gas by modulating the amount of oxygen input. The system of combustible gas production is capable of generating 241.67 GJ·h-1 of energy and attaining a cold gas efficiency of 81.62% when the ER is 0.25. The hydrogen production system can produce 1004.38 kg·h-1 of hydrogen and 206 t·h-1 of heated water at 0.5 MPa and 150℃ for an ER of 0.6. The optimum hydrogen production system achieved an energy efficiency of 90.97%, showing an improvement of 11.12% to 46.76% compared to previous hydrogen production systems. The standard Global Warming Potential of the system through carbon capture technology is 0.0087. The system developed in this paper benefits the industrial application of SCWPO and the optimization of subsequent processes. © 2024, The Authors. All rights reserved.

关键词： Thermolysis

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Thermodynamic Analysis of a Supercritical Water Partial Oxidation Autothermal Cogeneration System of Coal

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SSRN 2024年

作者： Xing, Guowei Li, Yifeng Ren, Changyifan Ge, Zhiwei Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Supercritical water partial oxidation (SCWPO) is a very efficient technology for the environmentally sound treatment of resources. Currently, there are few thermodynamic studies of SCWPO cogeneration system. In this study, a new supercritical water partial oxidation autothermal cogeneration system of coal is proposed. The system was evaluated for energy and exergy under typical operating conditions. The efficiencies achieved were 86% for energy and 47.6% for exergy. Due to the mixed working fluid is a mixture of H2O and CO2, the CO2 is very easy to capture. The exergy analysis revealed that the most significant exergy loss within the system occurred in the SCWPO reactor, which accounted for 78.2%% of the total exergy loss. Further sensitivity analysis of the system indicates that optimum values identified for both back pressure and carbon capture and storage unit (CCS) first stage pressure (PV-pump1), which are 8.5 kPa and 0.03 MPa. Additionally, increasing both the flow rate and temperature of preheated water can significantly enhance system efficiency. An increase in the flow rate of preheated water can lead to a reduction of the maximum system temperature;however, an elevation in the temperature of preheated water may cause a significant rise of the maximum system temperature, which is not conducive to the stable operation of the system. Finally, this paper compares the proposed system with the systems that have been reported in the literature. The results show that the system represents an innovative cogeneration solution with considerable advantages. © 2024, The Authors. All rights reserved.

关键词： Exergy

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Heat Transfer Enhancement of Air flow Through New Types of Perforated Dimple/Protrusion Fins

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SSRN 2024年

作者： Sen, Palash Chen, Mengjie Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Heat transfer enhancement technologies of air flow are of critical to energy conservation and emission reduction in industrial applications. This paper explores the numerical simulation analysis of 18 kinds of perforated dimple/protrusion fins. The wind speed varies within the range of 2~6m/s, and the investigation delves into the impact of different structural parameters on strengthening factor Nu/Nu0, resistance factor f/f0 and other comprehensive evaluation factor performance evaluation criteria (PEC) of perforated dimple/protrusion fins. The study specifically explores the influence of structural parameters, including intercepting perforated dimple/protrusion height (S0), aperture (D), hole structure offset (a), and the arrangement of perforated dimple/protrusion structure, on heat transfer performance. The overall heat transfer performance of the perforated dimple/protrusion fins rises with height under the same operating conditions. It first increases and then declines with the increasing aperture, and first drops and then increases with the increasing offset. The hole structure offset is better on the inflowing leeward side than on the inflowing side. The fins with both perforated dimple and perforated protrusion structures have advantages over the one with either of two structures, and the alignment arrangements are identified as the optimal configuration. © 2024, The Authors. All rights reserved.

关键词： Air

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Phase transfer-based high-efficiency recycling of precious metal electrocatalysts

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Green Chemical engineering 2024年第1期5卷 68-74页

作者： Qing Zeng Shaonan Tian Yu Zhang Hui Liu Dong Chen Xinlong Tian Chaoquan Hu Jun Yang State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing100190China State Key Laboratory of Marine Resource Utilization in South China Sea Hainan Provincial Key Lab of Fine ChemistrySchool of Chemical Engineering and TechnologyHainan UniversityHaikou570228China Nanjing IPE Institute of Green Manufacturing Industry Nanjing211100China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing100049China

Recycling precious metals with high-efficiency is undoubtedly beneficial to optimize resource utilization for environmental remediation and sustainable ***,we report an efficient route to recycle the palladium(Pd)and platinum(Pt)electrocatalysts using a phase transfer *** strategy involves acidic dissolution of deactivated precious metal(Pd/Pt)electrocatalysts from their loading substrates,mixing with an ethanolic solution of dodecylamine(DDA),subsequent extraction of metal ions into a non-polar organic phase,and final reduction by sodium borohydride to reproduce high-performance electrocatalysts towards typical electrochemical reactions,e.g.,oxygen reduction reaction(ORR)and ethanol oxidation reaction(EOR).In specific,the transfer efficiencies are up to 98%and the final recovery rate is over 85%for Pd and Pt electrocatalysts in each *** approach symbolizes a facile and efficient way to recover precious metals,which might be applied to recycling a wide range of metals in various realms after appropriate modifications.

关键词： Precious metal Phase transfer Extraction Recovery Electrocatalyst

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Calcium Looping Sorption-Enhanced Electrified Steam Methane Reforming for Efficient Hydrogen Production with Short- and Long-Duration Cooperative Energy Storage

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SSRN 2024年

作者： Song, Huchao Zhang, Xinyue Lin, Xiaolong Bian, Hao Liu, Yinhe State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Currently, the dominant hydrogen production technology is steam methane reforming, but both the reforming reaction and the combustion for driving the reaction produce significant CO2 emissions. Sorption-enhanced methane reforming enables the in-situ removal of CO2 produced by the reforming reaction and promotes higher hydrogen yields, however, CO2 emissions from combustion cannot be avoided. Renewable electricity instead of combustion for reaction heating can eliminate combustion carbon emissions and flue gas heat loss, but its dependence on renewable electricity supply prevents continuous and stable operation. This study proposes a sorption-enhanced electrified steam methane reforming technology based on short- and long-duration cooperative energy storage and calcium looping carbon capture. This technology utilizes the CO2 adsorption and energy storage property of the absorbent to absorb CO2 in situ in the reformer and transform renewable electricity to chemical and thermal energy in the regenerator as short- duration energy storage. The energy stored in the absorbent can be used to drive the methane reforming reaction and transformed into chemical energy in hydrogen continuously as long- duration energy storage. Through First law and Second law analysis, this study has found that the novel process improves thermal efficiency by 8.5 percentage points and reduces the exergy loss of the overall process by 53.2% compared with the sorption-enhanced steam methane reforming process. Based on current fuel prices in China, the novel process is more economical than the other steam methane reforming processes simulated in this study. Sensitivity analysis has found that low electricity and high methane prices benefit the economic performance of the novel process. This study may provide a stable, efficient, and economical way of clean hydrogen energy production. © 2024, The Authors. All rights reserved.

关键词： Hydrogen production

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High Concentration of CO and CO2 Inhibits Coal Gasification in Supercritical Water

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SSRN 2024年

作者： Zhang, Rui Zhao, Shuaiqi Huang, Han Zhao, Kunpeng Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Supercritical water gasification technology achieves efficient resource utilization of lignite and produces H2, CO and CO2. In this study, we experimentally investigated the impact of gas product generated from high concentration (>30 wt%) formic acid decomposition on the gasification of Tiebei lignite in the supercritical water. H2 promotes the pyrolysis of carbon structures, the increase in CO promotes CO2 generation through the water-gas shift reactions, and the enrichment of CO2 hinders gas diffusion. We found that high concentration of formic acid(H2, CO and CO2) inhibits the gasification of Tiebei lignite in the supercritical water. Compared with coal gasification in the supercritical water without formic acid, 30wt% formic acid reduces the carbon efficiency of lignite by 7.66%, and the mass conversion of coal by 3.97%. When the concentration of formic acid is 30wt% to 70wt%, the higher concentration of formic acid(H2, CO and CO2), the worse gasification performance of Tiebei lignite. © 2024, The Authors. All rights reserved.

关键词： Water gas shift

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Porous carbon material production from microwave-assisted pyrolysis of peanut shell

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Carbon Research 2023年第1期2卷 1-17页

作者： Qiu, Tianhao Li, Chengxiang Guang, Mengmeng Zhang, Yaning School of Energy Science and Engineering Harbin Institute of Technology Harbin150001 China State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing100190 China

Due to the complex porous structure, biochar usually has good adsorption capacity. Therefore, compared with direct combustion, conversion of peanut shell into biochar by pyrolysis is considered to be an environmentally friendly and efficient method for agricultural solid waste disposal. In this study, biochar production from microwave-assisted pyrolysis of peanut shell was detailed. The yields, surface topographies, and pore structures (pore size distribution and micropore volume) of biochars prepared at different pyrolysis temperatures (700, 750, 800, 850, 900, and 950 °C), microwave powers (350, 400, 450, 500, and 550 W), and residence times (0.5, 1.0, 1.5, 2.0, and 3.0 h) were elaborated. The results showed that the biochar yield gradually decreased and finally stabilized to around 30% while the specific surface area improved within the range of 4.68–67.29 m2/g when the pyrolysis temperature, microwave power, or residence time increased. Biochar with micropore was first obtained at pyrolysis temperature of 800 °C, microwave power of 500 W, and residence time of 2.0 h. This study further proposed quantitative relationships between the pore structures of peanut shell based biochars and experimental conditions (pyrolysis temperature, microwave power and residence time). The results presented in this study can provide guidance for the reuse of peanut shell and the production of porous biochar. The peanut shell biochar prepared in this study can be used in soil remediation, air purification, liquid purification and other fields for its porous structural characteristics. © 2023, The Author(s).

关键词： Waste incineration

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Electrochemical evolution of a metal oxyhydroxide surface on two-dimensional layered metal phosphorus trisulfides enables the oxidation of amine to nitrile

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Carbon Energy 2025年第3期7卷 133-147页

作者： Binglan Wu Karim Harrath Marshet Getaye Sendeku Tofik Ahmed Shifa Yuxin Huang Jing Tai Fekadu Tsegaye Dajan Kassa Belay Ibrahim Xueying Zhan Zhenxing Wang Elisa Moretti Ying Yang Fengmei Wang Alberto Vomiero State Key Laboratory of Chemical Resource Engineering College of ChemistryBeijing University of Chemical TechnologyBeijingChina CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology(NCNST)BeijingChina Shaanxi Provincial Key Laboratory of Electroanalytical Chemistry Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of EducationCollege of Chemistry&Materials ScienceNorthwest UniversityXi'anChina State Key Laboratory of Multiphase Flow in Power Engineering International Research Center for Renewable EnergyXi'an Jiaotong UniversityShaanxiChina Fundamental Science Center of Rare Earths Ganjiang Innovation AcademyChinese Academy of ScienceGanzhouChina Ocean Hydrogen Energy R&D Center Research Institute of Tsinghua University in ShenzhenShenzhenChina Department of Molecular Sciences and Nanosystems Ca'Foscari University of VeniceVenezia MestreItaly Testing and Analysis Center Institute of Chemistry Chinese Academy of SciencesBeijingChina Department of Engineering Sciences and Mathematics Division of Materials ScienceLuleåUniversity of TechnologyLuleåSweden

Selective oxidation of amines to imines through electrocatalysis is an attractive and efficient way for the chemical industry to produce nitrile compounds,but it is limited by the difficulty of designing efficient catalysts and lack of understanding the mechanism of ***,we demonstrate a novel strategy by generation of oxyhydroxide layers on two-dimensional iron-doped layered nickel phosphorus trisulfides(Ni1-xFexPS_(3))during the oxidation of benzylamine(BA).In-depth structural and surface chemical characterizations during the electrocatalytic process combined with theoretical calculations reveal that Ni(1-x)FexPS_(3) undergoes surface reconstruction under alkaline conditions to form the metal oxyhydroxide/phosphorus trichalcogenide(NiFeOOH/Ni1-xFexPS_(3))***,the generated heterointerface facilitates BA oxidation with a low onset potential of 1.39 V and Faradaic efficiency of 53%for benzonitrile(BN)*** calculations further indicate that the as-formed NiFeOOH/Ni1-xFexPS_(3) heterostructure could offer optimum free energy for BA adsorption and BN desorption,resulting in promising BN synthesis.

关键词： 2D layered materials benzylamine oxidation metal phosphorus trichalcogenides surfacereconstructed heterostructure

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Performance Analysis of Low GWP Refrigerants R1234yf and R448A in a Small High and Low-temperature Test Equipment

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Recent Patents on Mechanical engineering 2022年第3期15卷 277-284页

作者： Liqiang, Zhou Zhang, Hua Zilong, Wang Wenjing, Gao School of Energy and Power University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

Aim: The article presents an analysis of the feasibility of R1234yf and R448A, two new low GWP refrigerants, as alternatives to R404A in the refrigeration system of small high and low-temperature test equipment. Methods: The physical properties of R448A and R404A are similar. Compared with R404A, the GWP of R1234yf and R448A reduced by 99.9% and 67.7%, respectively. The analysis is based on an experimental comparison of R404A with R448A and R1234yf, comparing the compressor discharge tempera-ture, COP, cooling capacity, and the cooling rate of three refrigeration systems at different ambient temperatures. Results: The experimental results show that the cooling capacity of R448A is better than R404A at a higher condensing temperature. Conclusion: When the charging volume is 230g, and the ambient temperature is 25°C, the COP of the R448A system is increased by about 24.63% compared with the R404A system. © 2022 Bentham Science Publishers.

关键词： Refrigerants

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